The invention concerns a device for breeding fish, shellfish, etc. in tanks lowered into water.
In the most common type of fish breeding today, the fish is contained in nets lowered into the sea, a lake or a water current. Fresh water is then continuously fed which is a condition for the breeding, unless special purification plants are used.
The disadvantages with such systems are several. Purifications and food waste may be collected at the bottom under the net, poison the surroundings and sometimes even the fish. In addition there is often a large waste of food and the nets must quite often be cleaned from algae. Finally, the breeding is dependent on the temperature of the surrounding water as well as on the contents of oxygen and natural nourishment therein. These conditions are of course dependent on the season which means that the growth is sometimes very low.
Fish breeding in closed tanks provided with purification plants has up to now turned out to be too expensive to be utilized on a large scale, primarily becausae the breeding must take place on land.